Garmin Forerunner 645 vs Polar Ignite

Garmin Forerunner 645 vs Polar Ignite

This is a simple product comparison between the Garmin Forerunner 645 vs Polar Ignite.

While they are both excellent GPS watches packed with features and made by two of the best brands in the business, our feeling is that the Forerunner 645 is definitely the better choice for serious runners. However, the Polar Ignite is actually the more well rounded watch for sports and fitness enthusiasts. 

To help you choose the right watch, we’re going to unpack all the key differences, and all the key similarities, with a few straightforward recommendations at the end. 

What are the main differences between Forerunner 645 and the Polar Ignite?

  1. The Polar Ignite has a touchscreen, the Garmin Forerunner 645 only uses buttons. Serious runners tend to prefer buttons over touchscreens, at least when exercising.
  2. The Forerunner 645 can store music on the watch, and it can also play music through apps like Spotify and Deezer.
  3. The Polar Ignite offers more Sports Modes (100+), while the Foreunner 645 is limited to 19 sports and activity modes.
  4. The FR645 supports running power through 3rd party devices like Stryd and Runscribe, whereas the Polar Ignite does not.
  5. The Forerunner 645 also offers support for Garmin running power. 
  6. The optical (wrist-based) heart rate monitor on the Polar Ignite is a bit more accurate than the optical heart rate monitor on the Forerunner 645.
  7. Both watches can track pool swimming, but only the Polar Ignite can track open water swimming. Neither watch has a triathlon mode.
  8. The Forerunner 645 has a built-in barometric altimeter. This makes it better for measuring vertical movements during running, cycling and hiking. 

Ok. We’ve covered most of the important high level differences. Now let’s jump into the details with some simple comparison tables. 

Garmin Forerunner 645 vs Polar Ignite - Key Similarities

Garmin FR645

Polar Ignite


Wrist-Based HRM

24/7 Activity Tracking

Stress Tracking

Smartphone Notifications

Indoor + Outdoor Running

Indoor + Outdoor Cycling

Pool Swimming

Indoor + Outdoor Rowing

Strength + Cardio Training

Customized Running Plans

Triathlon Mode

Garmin Forerunner 645 vs Polar Ignite - Key Differences

Garmin FR645

Polar Ignite


More Expensive

Less Expensive

Physical Size

42.5 x 42.5 x 13.5 mm

43 x 43 x 8.5 mm

Lens Material

Corning® Gorilla® Glass 3

Dragontrail Glass Lens

Screen Resolution

240 x 240 pixels

240 x 204 pixels


42.2 g

35 g

Galileo Satellite

Music Storage & Apps

Advanced Running Dynamics

Body Battery Score

ANT+ & WiFi

Safety Tracking

Menstrual Tracking

Barometric Altimeter

Running Power

Garmin + Stryd + RunScribe

Not Compatible


Polar FitSpark

Guided Breathing

Open Water Swimming

Total Sports Modes



GPS Battery

Up to 14 Hours

Up to 17 Hours

Main Reason To Choose the Forerunner 645


Music Storage & Music Apps

The Forerunner 645 includes 3.5GB of in-built music storage which works out to about 500 songs. In addition, you can also play music on the FR645 using popular music apps such as:

  • Spotify
  • Deezer
  • iHeartRadio
  • Amazon Music

Support for Running Power through Garmin, Stryd and RunScribe

This could be the biggest difference between the two watches. The Garmin Forerunner 645 supports 3rd party  running power meters including Stryd & Runscribe, whereas Polar Ignite doesn’t.

In addition, the Forerunner 645 also supports Garmin running power. This is worth noting, because the accessories which unlock Garmin running power are significantly cheaper than the 3rd party running power accessories. Also, when you choose the Garmin accessory to access running power, you get a massive bonus benefit of unlocking advanced running dynamics at the same time. 

Take note: In order to unlock Garmin Running Power on the Forerunner 645, you need to invest in one of the following accessories:

If you want to unlock running power with a 3rd party accessory, these are the options: 

Button Only Interface - Forerunner 645

The Garmin Forerunner 645 relies exclusively on buttons to move between screens, activate workout modes and interact with the watch. Even though this limits its capabilities as a Smartwatch, it enhances its appeal as a running/fitness watch.

When you step into your exercise mode of choice, having buttons is actually a lot more convenient than having a touchscreen. This is mainly because sweaty palms and fingers can make it a bit clumsy to use a touchscreen in the middle of an exercise session. 

WiFi & ANT+ Connectivity - FR645 Only

It’s a bit crazy that Polar don’t offer ANT+ support for any of their watches at this moment in time (Polar Ignite included). The end result is that you’re limited mainly to the Polar accessory ecosystem, which can be limiting at times.

On the other hand, the Forerunner 645 offers ANT+ support for various 3rd party accessories and it also boast WiFi connectivity as well. 

Main benefit of ANT+ Connectivity: You get access to a bunch of different cycling accessories that communicate with the Forerunner 645 via ANT+.

Main benefit of WiFi Connectivity: It makes transferring data from your watch to your phone or computer significantly faster. 

Advanced Running Dynamics - FR645 Only

This is another impressive feature that’s only available if you choose Garmin Forerunner 645. The advanced running metrics that Garmin offers are pretty cool if you’re big into running. These are the stats that you can unlock with the FR645.

  • Ground Contact Time – The time your foot spends on the ground with each stride. 
  • Ground Contact Balance – Symmetry between left and right foot. 
  • Vertical Oscillation – Degree of ‘bounce’ in your running motion. 
  • Vertical Ratio – the cost-benefit ratio with stride length. 
  • Cadence – Real time display of running cadence displayed on the FR645 screen. 
  • Stride Length – Real time display of stride length on the FR645 screen. 

However, there is a slight catch. In order to unlock these metrics, you need invest in one of the following three Garmin Accessories (these are the same accessories that unlock Garmin Running Power). 

  1. Garmin HRM-Run – Best for runners who want near perfect heart rate data.
  2. Garmin HRM-Tri – Best choice for triathletes.
  3. Garmin Advanced Running Dynamics Pod – Best choice for people on a tight budget.

Support for Manual Laps

There are plenty of serious runners that have been annoyed by Polar’s decision to remove manual lap tracking from the Polar Ignite. 

Fortunately this feature is found in the Forerunner 645. The bullet points below should make things pretty clear:

  • Polar Ignite: Automatic laps only
  • Garmin Forerunner 645: Manual laps + Automatic laps

Main Reasons To Choose the Polar Ignite


80 Additional Sports Modes

The Forerunner 645 is actually pretty decent when it comes to sports tracking, but it can’t compete with the total number of sports modes offered by the Polar Ignite. The table below demonstrates that the Ignite can do pretty much everything that the FR645 can do, and more. 

Comparison of Sports Modes - FR645 vs Polar Ignite

Forerunner 645 Sports Modes Polar Ignite Sports Modes
01) Strength Training 01) Strength Training
02) Cardio Training 02) Cardio Training
03) Elliptical Training 03) Elliptical Training
04) Stair Stepping 04) Stair Stepping
05) Indoor Rowing 05) Indoor Rowing
06) Yoga 06) Yoga
07) Running 07) Running
08) Treadmill Running 08) Treadmill Running
09) Indoor Track Running 09) Indoor Track Running
10) Trail Running 10) Trail Running
11) Cycling 11) Cycling
12) Indoor Cycling 12) Indoor Cycling
13) Pool Swimming 13) Pool Swimming
14) Walking 14) Walking
15) Snowboarding 15) Snowboarding
16) Skiing 16) Skiing
17) Cross Country Skiing 17) Cross Country Skiing
18) Stand Up Paddleboarding 18) Windsurfing
19) Outdoor Rowing 19) Outdoor Rowing
20) Golf Mode
21) 100+ Additional Modes

Touchscreen - Polar Ignite Only

We’ve already “touched” on this, but it’s worth repeating. The Polar Ignite relies exclusively on a touchscreen for all interactions with the watch.

Interestingly, this is probably the biggest weakness of the Ignite. The touchscreen is perfectly functional, but some users have reported issues with ‘waking’ the screen. To explain further, the colour screen of the Polar Ignite isn’t ‘always on’. Instead, it only activates when you raise the watch to glance at the screen.

Polar might be able to resolve this via a firmwire update in future, but for now, the inconsistency of the rise to wake feature is probably the single biggest weakness of the Polar Ignite. Fortunately you can get around it by simply touching the screen, but still, it would be nice if the rise to wake feature work 99% of the time, and right now it doesn’t. 

FitSpark Workout Recommendations - Polar Ignite Only

FitSpark is a bit like a virtual personal trainer that has been studying your training metrics for weeks on end. It then uses all this data to create customized workout plans that can help you reach even greater levels of fitness.

For people who are willing to let their watch guide them through a workout, FitSpark is literally as good as it gets. Garmin have actually released something similar called ‘Guided Workouts’ but this is only available on the Garmin Vivoactive 4 and the Garmin Venu at this point in time. 

Open Water Swimming - Polar Ignite Only

As mentioned in the beginning, both watches track pool swimming with SWOLF stats to boot. However, the Ignite has an extra trick up it’s sleeve with the inclusion of Open Water Swimming. The bullet points below should help clear up any confusion: 

Garmin Forerunner 645: Pool Swimming Only

Polar Ignite: Pool Swimming + Outdoor Swimming

Despite being able to track running, cycling and open water swimming, the Ignite doesn’t have a multisport mode (neither does the FR645). This is mainly because it would be too close to the Vantage M if Polar made this feature available to users (it would eliminate the need to upgrade to the more expensive model).

So which one should you buy?

Go for the Forerunner 645 if..

  • You take your running seriously
  • You want access to advanced running dynamics and running power
  • You’re an avid cyclist (ANT+ connectivity being the main benefit for cyclists)
  • You want the ability to play music on your watch during workouts

Go for the Polar Ignite if...

  • You’re on a tight budget
  • You want the watch with the most sports modes
  • You don’t mind using a touchscreen
  • Running isn’t your primary sport (if it is, the FR645 is the better choice)
  • You are likely to use the open water swimming feature

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